1. Field of the Invention
The present invention relates to X-ray apparatus, and more particularly it relates to multichannel X-ray spectrometers.
2. Description of the Prior Art
The invention can be used for prompt analysis of elementary compositions of substances by X-ray spectrometry techniques, e.g. in ferrous and non-ferrous metallurgy for determining the grades of and marking correspondingly various steels, brasses, iron; for sorting out materials and products, e.g. tubes, pipes, rolled sheet, plate or shapes in storage; for determining the main components and harmful impurities in intermediate and final products of mining and mineral-processing; in production of chemicals, cement or ceramics; in general engineering; in aircraft and engine engineering for analysis of engine performance; in analysis of fuels and lubricants; in medicine and biology for environment pollution control.
There is known a multichannel X-ray spectrometer which includes an X-ray tube, a holder for a specimen under investigation, facing the target of the tube, and spectrometric channels arranged about the X-ray tube and including respective inlet slits, focusing analyzer crystals, outlet slits and X-ray detectors, successively arranged in the direction of the fluorescent X-rays emitted by the specimen under investigation (ARL, USA, Quantometer--72000, 1980).
In this known spectrometer, each spectrometric channel has its own inlet slit of a rectangular shape. The distances from the target of the X-ray tube to the specimen holder and from the specimen to the inlet slits of the spectrometric channels exceed a hundred millimeters. The low relative aperture efficiency ratio of this spectrometer necessitates the incorporation of a relatively high-power X-ray tube (as powerful as 3 to 5 kW), while the design where the spectrometric channels have their own inlet slits is complicated and significantly steps up the weight and dimensions of the spectrometer (its weight being about 2000 kilograms).
There is also known a multichannel X-ray spectrometer which includes an X-ray tube with a transmission target, a holder for a specimen under investigation, facing the target of the tube, and spectrometric channels arranged about the X-ray tube and including respective inlet slits, focusing analyzer crystals, outlet slits and detectors of X-rays, successively arranged in the direction of fluorescent X-rays emitted by the specimen under investigation (V/O TECHSNABEXPORT, USSR, Portativny avtomatichesky mnogokanalny rentgenovsky spektrometr ARK, Moscow, 1981).
In this spectrometer each spectrometric channel likewise includes its own inlet slit of a rectangular shape, the inlet slits of the spectrometric channels being spaced from the specimen holder by a distance r not exceeding one fourth of the product of multiplication of the diameter D of the focusing circle of the focusing analyzer crystal by the ratio of the height H of the analyzer crystal to its length L, i.e. EQU r.ltoreq.DH/4L.
Owing to small distances from the target of the X-ray tube to the specimen holder and from the specimen to the inlet slits (as small as several millimeters) and to the arrangement of the inlet slits, analyzer crystals and outlet slits along a focusing circle of the diameter D, this spectrometer offers a high-efficiency aperture ratio, small dimensions and weight.
However, the design of the spectrometric channels with rectangular inlet slits would not provide for arranging about the X-ray tube an increased number of spectrometric channels (practically, in excess of six).
An increased number of spectrometric channels (e.g. twelve channels), on the other hand, can be accommodated by arranging the channels one on top of another, but this would complicate the structure of the spectrometer and increase its dimensions and weight.